One-component diazotype material



United States Patent 7 Claims. 2C1. 96-75) The invention relates toone-component diazotype material,

Iii practice one-component diazotype materials which have beensensitized with 4-diazo-2-chloro-N,N-diethylvaniline are used on a largescale. They are developed according to the so-called thin-layer methodwith weakly alkaline developing liquids which contain phloroglucinol, ifdesired together with resorcinol, and then yield copies with brownazo-dyestufr images that have high absorption for ultraviolet rays andare extremely suitable for use as intermediate originals if the supportmaterial is translucent.

The brown colour of the azo-dyestuff of the copies on these diazotypematerials, developed with weakly alkaline phloroglucinol developer, isnot appreciated by all users of these materials. Many of them considerit too light. The copies sometimes show bleeding of the azo-dyestuff, inconsequence of which the images are less sharp. This bleeding may be dueto the dissolution of the diazo compound in the developing liquid duringdevelopment, the azo-dyestutf formed from the dissolved diazo compoundbeing deposited beyond the azo-dyestuif portions of the image on thesurface of the copy. It may also be due to the azo-dyestuff formed inthe azo-dyestutf portions being washed away with the developing liquid.

The bleeding occurs, for instance, if foam is formed in the developingliquid during the development of the copies. These diazotype materialsare not suitable for development with weakly acid bufferedphloroglucinol developers, because the diazo compound does not couplesufficiently actively. As is known, weakly acid buffered phloroglucinoldevelopers have better keeping qualities than weakly alkalinephloroglucinol developers.

The South African Patent No. 3,627/60 describes onecomponent diazotypematerial which comprises a diazo film layer, sensitized with a diazocompound that couples more actively than4-diazo-2-chloro-N,N-diethylaniline. This diazotype material can bedeveloped with weakly acid liquids containing phloroglucinol and, ifdesired, resorcinol, which liquids have been buffered with a salt of astrong base and a dicarboxylic acid such as succinic acid, glutaricacid, adipic acid, and fi-methyladipic acid.

The said South African patent describes, among other things, transparentdiazotype material with a diazo film layer in which4-diazo-2-chloro-N-methyl-N-cyclohexylaniline is present as diazocompound. This material is developed with a liquid which containsphloroglucinol and resorcinol as azo components and a mixture of sodiumsuccinate, succinic acid, and sodium benzoate as buffer. The pH of thisliquid is 6.6. After the application of the developing liquid the copyis dried while heating moderately. Upon development, copies are obtainedwith strong, dark violet-brown azo-dyestuif images on a cleartransparent background. The azo-dyestuff has very good absorption forultraviolet light and hardly bleaches upon prolonged or repeatedexposure to this light.

For the development of diazotype materials sensitized with4-diazo-2-chloro N methyl N cyclohexylaniline, either in a film layer ornot, with a weakly acid phloroglucinol developer, the use of the saidspecial weakly acid buffered phloroglucinol developer is more or lessrequired and the copies have to be heated after the application of thedeveloping liquid in order to ensure proper development. Nevertheless,the developing speed of these materials is often too slow for practicalpurposes (even when the said special developer is used) if theirlight-sensitive layer contains the diazo compound in the form of thezinc chloride double salt together with the stabilizer 1,3,6-naphthalene trisulphonic acid or a water-soluble salt thereof. The useof the zinc chloride double salt of the diazo compound together withthis stabilizer is highly desirable, because these diazotype materialsotherwise are not very durable.

When the zinc chloride double salt of the diazo compound is used,however, the material is developed much less satisfactorily according tothe thin-layer method than when, for instance, the chloride or thetwo-basic sulphate is used.

Moreover 1,3,6-naphthalene trisulphonic acid retards the couplingactivity of 4-diazo-2-chloro-N-methyl-N- cyclohexylaniline in a highdegree. The degree of re tardation is indeed dependent on the quantityof stabilizer that is added, but it is already considerable uponaddition of the usual quantity desirable for good stabilization.

If with a weakly acid buffered phloroglucinol developer a properdevelopment of copies on diazotype material sensitized with the zincchloride double salt of 4-diazo-2- ohloro-N-methyl-N-cyclohexylanilinecontaining a conventional quantity of 1,3,6-naphthalene trisulphonicacid is to be obtained, it is necessary to provide, for instance, for arelatively high temperature of the developing liquid, such as 30 to 35C., or for thorough heating of the copy wetted with the developingliquid, or for the application of a thick layer of developing liquid,such as 12 g./m. on the surface of the copy, or for a large quantity ofphloroglucinol in the developing liquid.

The retarded developing speed may have all sorts of harmfulconsequences, Thus the visual and the transmission contrast of a copywhich has been exposed to daylight for some time, for instance, may beconsiderably lower than that of a freshly developed copy, because thediazo compound that has not been converted into azodyestuff duringdevelopment bleaches gradually. Furthermore the copies which originallyhad a clear background are often found to show fogging in the backgroundportions after a few minutes in consequence of the slowness with whichthe development proceeds in those portions in which after the imagewiseexposure only a small amount of diazo compound is left. Consequently,the quality of the copies can only be judged some time afterdevelopment, a circumstance which is naturally very inconvenient inpractice. Moreover the copies often show bleeding.

From Dutch patent specification 36,214 one-component diazo-type materialis known which has been made lightsensitive with 4-diazo 2,5dichloro-N-(2',6-dichloro)- benzyianiline. This material is developedwith a weakly alkaline phloroglucinol-containing liquid, but it is onlyslightly light-sensitive according to present-day standards. The diazocompound does not couple sufficiently actively for the development ofthe diazotype material sensitized with it, according to the thin-layermethod with a weakly acid buffered phloroglucinol developer.

From FIAT Report 813, page 1349, the compound 4-diazo-2,S-dichloro-N-ethyl-N-benzylaniline is known. No statement ismade about its properties and about those of diazotype materialsensitized with it. From a test, however, it appeared that this diazocompound forms a precipitate with 1,3,6-naphthalene trisulphonic acid inthe conventional aqueous sensitizing liquids, so that it is not possibleto use this diazo compound for making diazotype paper containing thisstabilizer in the usual way.

Paper with this diazo compound without this stabilizer has very poorkeeping qualities.

Now it has been found that one-component diazotype material containing adiazo compound of the general formula methyl XN N cyclohexyl R 2 inwhich X is an anion, R and R are chlorine or bromine atoms, and thecyclohexyl group may be substituted by one or more methyl radicals, canbe stabilized in the usual way with 1,3,6-naphthalene trisulphonic acidor a salt thereof, without the coupling activity of the diazo compound,in this case the developing speed of the diazotype material, decreasingin a degree that is inconvenient for practical purposes.

The diazotype material according to the invention is verylight-sensitive and it can be developed with weakly acid bufleredphloroglucinol-containing developing liquids to form dark, almost blackazo-dyestuffs which have high absorption for actinic radiation, and withweakly alkaline phloroglucinol-containing developing liquids to formfine dark-brown azo-dyestuffs which also have high absorption foractinic radiation.

The azo-dyestuff images obtained with weakly acid bufferedphloroglucinol developers do not, or in a much less degree, show theabove-mentioned phenomena, which point to incomplete development. Whendiazotype material according to the invention is used, bleeding of theazo-dyestuff image occurs in a much less degree than when diazotypematerial sensitized with 4-diaZo-2-chlorodiethylaniline or 4 diazo 2chloro N-methyl-N-cyclohexylaniline is used.

The support of the diazotype material according to the invention may beopaque, such as paper, linen, lacquered paper, or translucent, such astracing paper that may or may not be lacquered, tracing linen, celluloseacetate and polyester film. If the support surface is hydrophobic, thediazo compound is preferably applied in a hydrophilic film layer whichcovers the hydrophobic surface. If the support is transparent or atleast translucent, the copies are very suitable as intermedaiteoriginals, irrespective of whether they are developed with a weakly acidor with a weakly alkaline phloroglucinol developer.

Very attractive material is one-component diazotype material accordingto the invention which comprises a transparent support, such as naturaltracing paper, tracing linen, or polyester film that has been coatedwith a film layer formed from a hydrophilic colloid obtained byhydrolysis of an ester of the group formed by cellulose and polyvinylesters, in which film layer the diazo compound is present along withl,3,6-naphthalene trisulphonic acid or a water-soluble salt thereof.

This diazotype material has good keeping qualities, is developedpractically completely within a short time with a weakly acid bufieredphloroglucinol-containing developing liquid according to the thin-layermethod, and yields sharp copies with strong dark azo-dyestutf images,which have high absorption for ultraviolet light. The azo-dyestuffimages of the copies can be readily erased, for instance by scraping offthe film layer with a blade.

The keeping qualities of diazotype material according to the inventionin which the diazo compound is present in the form of the zinc chloridedouble salt along with 1,3,6-naphthalene trisulphonic acid or awater-soluble salt thereof in a hydrophilic film layer as describedabove are particularly good. Notwithstanding the use of the diazocompound in the form of the zinc chloride double salt, such diazotypematerial is developed sufiiciently rapidly with the weakly acid bufferedphloroglucinol-containing developing liquids.

Diazo compounds which are suitable for application in the diazotypematerial according to the invention are, for instance:

4-diazo-3,6-dichloro-N-methyl-N-cyclohexylaniline 4-diazo-3,6-dibromo-N-methyl-N-cyclohexylaniline4-diazo-3-chloro-6-bromo-N-methyl-N-cyclohexylaniline4-diazo-3,6-dichloro-N-methyl-N- (methyl) cyclohexylaniline They can beused separately, mixed together, or mixed with another diazo compound.

They can be prepared as follows: 4-nitro-2-chloroaniline is diazotizedand the diazo group is replaced by a chlorine or bromine atom bysandmeyering. The nitro group of the product obtained is reduced to anamino group, which is acetylated with acetic anhydride. In the3-chloro-4-(chloro or brom0)acetanilide thus produced a nitro group isthen introduced and the acetylamino group is deacetylated by boilingwith hydrochloric acid, after which the 4-(chloro or bromo)-5-chloro 2nitroaniline thus obtained is converted with N-cyclohexylamine into5-cyclohexylamino 4 (chloro or bromo)-2-nitroaniline, from whichcompound 4-nitro-2-(chloro or bromo)-5- (chloro orbromo)-N-methyl-Ncyclohexylaniline is then obtained by diazotization,sandmeyering to chloro or bromo, and methylation with formic acidformaldehyde. Finally the nitro group is reduced and the amino compoundobtained is diazotized, so that 4-N-methyl-N-cyclohexylamino-3-(chloroor bromo)-6-(chloro or bromo)- diazobenzene is obtained, which can bemade available in the form of a salt, such as the zinc chloride doublesalt, chloro stannate, or boro fluoride.

The diazotype material according to the invention may contain theauxiliary agents commonly used in one-component diazotype material, forinstance acids such as citric acid, boric acid, tartaric acid,stabilizers such as 1,3,6- naphthalene trisulphonic acid and itswater-soluble salts, reducing agents such as thiourea, metal salts suchas aluminum sulphate, synthetic resin dispersions, silica disperions,etc.

Example I Sized natural tracing paper is sensitized with a liquidcontaining:

64 g. of 4-N-methyl-N-cyclohexylamino-3,6-dibromobenzene diazoniumchloride, zinc chloride double salt 5 g. of tartaric acid 20 g. of1,3,6-naphthalene trisulphonic acid sodium salt 30 ml. of polyvinylacetate dispersion Vinnapas H. 60

from Wacker-Chemie G.m.b.H., Munich 1000 ml. of water and dried.

The transparent diazotype paper thus prepared is very light-sensitiveand has good keeping qualities.

A sheet of the diazotype material is imagewise exposed underneath an inktracing until underneath the blank portions of the tracing all the diazocompound has been bleached out, and then developed according to thesocalled thin-layer method with a weakly acid liquid containing:

10 g. of thiourea 6.5 g. of phloroglucinol 4 g. of resorcinol 2 g. ofisopropylnaphthalene sulphonic acid sodium salt 14 g. of sodium formate22 g. of sodium benzoate 47 g. of sodium citrate, 2 aq.

1.2 g. of citric acid 1000 ml. of water The developing liquid has a pHof about 6.2.

The copy obtained shows a strong violet-black azo-dyestuff image on aclear background and is eminently suitable for use as an intermediateoriginal for making further copies. The azo-dyestuff image does notbleed upon development.

If instead of the above-mentioned diazo compound the zinc chloridedouble salt of 4-N-methyl-N-cyclohexylamino-3-chlorobenzene diazoniumchloride had been used in an equivalent quantity, a less rapidlydeveloping diazotype material of approximately the samelight-sensitivity would have been obtained, which yields copies withsome what lighter azo-dyestuff images, having good absorption forultraviolet radiation, but showing some bleeding upon development.

Another sheet of the diazotype material is imagewise exposed asdescribed above and then developed with a weakly alkaline liquid of thefollowing composition:

30 g. of thiourea 5.4 g. of phloroglucinol 6.5 g. of resorcinol 1 g. ofhydroquinone monosulphonic acid potassium salt 5 g. of sorbitol g. ofsugar 50 g. of potassium tetraborate, 5 aq.

1.5 g. of isopropylnaphthalene sulphonic acid sodium salt 1000 ml. ofwater The developing liquid has a pH of about 9.5.

The copy obtained shows a strong, sharp, and fine darkbrown azo-dyestuffimage, the azo-dyestuff of which has high absorption for ultravioletradiation.

Example 11 A cellulose acetate film layer of about g./m., applied onnatural tracing paper of about 80 g./m. is superficially hydrolysed to adepth of about 4 microns and, after washing with water to remove thechemicals used for the hydrolysis, is sensitized with a solution of:

65 g. of 4-N-methyl-N-cyclohexylamino-3,6-dichlorobenzene diazoniumchloride, zinc chloride double salt 2 g. of boric acid 4 g. of tartaricacid 20 g. of 1,3,6-naphthalene trisulphonic acid sodium salt 250 ml. ofethanol (96%) 750 ml. of water and dried.

The diazotype material obtained is very light-sensitive and hasexcellent keeping qualities.

A sheet of the diazotype material is imagewise exposed as in Example Iand developed with the weakly acid developing liquid mentioned in thatexample. The diazotype material has a markedly greater developing speedand yields markedly sharper and even darker-coloured azo-dyestutf imagesthan corresponding diazotype material which contains an equivalentquantity of the zinc chloride double salt of4'N-methyl-N-cyclohexylamino-3- chlorobenzene diazonium chloride.

Upon development with the weakly alkaline developing liquid described inExample I, the new diazotype material yields transparent copies with astrong dark-brown azo-dyestuft image, the azo-dyestuff of which has highabsorption for ultraviolet radiation.

Example III White base-paper of 80 g./m. for the diazotype process issensitized on one side with a solution of g. of4-N-methyl-N-(methyl)cyclohexylarnino-3,6-dichlorobenzene diazoniumchloride, zinc chloride double salt 5 g. of tartaric acid 30 g. of1,3,6-naphthalene trisulphonic acid sodium salt 30 ml. of Vinnapas H. 60in 1000 ml. of water and dried.

The diazotype paper obtained is very light-sensitive and has excellentkeeping qualities.

A sheet of the diazotype paper is imagewise exposed as in Example I andthen developed with a thin layer of the weakly acid developing liquiddescribed in Example I. The copy shows a sharp and strong violet-blackazo-dyestuif image on a clear white background.

If the new diazotype material is developed with the weakly alkalinedeveloping liquid described in Example I, the azo-dyestuif image has afine dark-brown shade.

A copy on a diazotype paper sensitized with a liquid of the samecomposition, but containing instead of the above-mentioned diazocompound an equivalent quantity of4N-methyl-N-cyclohexylamino-3-chlorobenzene diazonium chloride, zincchloride double salt, if also developed with the weakly acid developingliquid, shows an incompletely developed, rather weak azo-dyestuff image,which moreover shows some bleeding of the lines.

Example IV White paper of 150 g./m. provided on one side with acellulose acetate film layer (approximately 50% by weight of combinedacetic acid) of a thickness of about 10 microns, which has been fixed tothe paper by means of an adhesive and which has been deacylated to adepth of about 4 microns to an average acetyl content, calculated ascombined acetic acid, of approximately 20% by weight (which correspondsto an average number of acyl groups on the OH-- groups of 0.7), isimpregnated for 2.5 minutes on the deacylated side of the celluloseacetate layer with the following solution:

sodium salt and thus sensitized.

The excess of liquid is removed from the cellulose acetate surface andsubsequently the material is dried. The diazotype material obtained isvery light-sensitive and has good keeping qualities.

A sheet of the diazotype material is imagewise exposed as in Example Iand developed with the weakly acid developing liquid described in thatexample. The copy obtained shows a very strong violet-blackazo-dyestufif image, which did not bleed upon development. If instead ofthe weakly acid developer the weakly alkaline phloroglucinol developerdescribed in Example I had been used, a copy with a very strong, finedark-brown azodyestutf image would have been obtained.

If a similar sheet is sensitized in the same way with a solution of thesame composition, but containing instead of the above-mentioned diazocompound an equivalent quantity of4-N-methyl-N-cyclohexylamino-3-chlorobenzene diazonium chloride, zincchloride double salt, a diazotype material is obtained which developsmarkedly less rapidly and yields copies with a dark red-brownazodyestutf image would have been obtained. is eifected with the weaklyacid developer, and copies with a light-brown azo-dyestutf image ifdevelopment is carried out with the weakly alkaline developer.

Example V Tracing linen of the Red Bridge Sub./0/86 type from Red BridgeBook Cloth Company, Red Bridge, Ainsworth, Bolton, England, is coated byimmersion with a layer of about 70 g./m. of the following liquid:

g. of polystyrene copolymer Lutron X820 from Monsanto Chemical Company,Plastics Division, Springfield 2, Massachusetts, USA.

30 g. of polyvinyl acetate Rhodopas H.V. 2 from Rhone- Poulenc, Paris,France 50 ml. of ethyl acetate 900 ml. of ethanol (96%) After drying, alayer of about 80 g./m. of the following liquid is applied on thehydrophobic adhesive layer thus formed:

40 g. of partially (about 53%) hydrolysed polyvinyl acetate VinnapasU.W. 50 from Wacker-Chemie G.m.b.H., Munich 2, Germany 20 g. of Gelvatol4020, a partially hydrolysed polyvinyl acetate from Shawinigan ProductsCorp, New York 1, U.S.A.

g. of isopropylnaphthalene sulphonic acid sodium salt Aerosol OS fromAmerican Cyanamid Co., New York 20, USA.

500 ml. of ethanol (96%) 500 m1. of Water After drying, a hydrophilicpolyvinyl acetate layer of a thickness of about 4.5 microns is presenton the adhesive layer.

Subsequently a sensitizing liquid is prepared as follows.

To a solution containing:

3.25 g. of 4-N-methyl-N-cyclohexylamino 2,5 dichloroaniline 3 ml. ofhydrochloric acid (S. G. 1.19)

50 ml. of water of 0 C.

is added dropwise, with continuous stirring, while the solution is keptat a temperature of 25 C., such a quantity of a solution of:

30 g. of sodium nitrite in 100 ml. of water that exactly all the aminocompound is converted into the corresponding diazonium compound. To thediazonium chloride solution are then added 0.5 g. of tartaric acid 3 g.of naphthalene trisulphonic acid sodium salt 40 ml. of ethanol (96%) and7 ml. of Water The hydrophilic polyvinyl acetate layer is impregnatedwith this sensitizing liquid.

The hydrophilic light-sensitive layer obtained after drying containsapproximately 0.8 millimol of diazo compound per m. of the sensitizedsurface.

A sheet of the transparent diazotype linen thus produced is imagewiseexposed as in Example I and developed with the weakly acid developingliquid.

The copy obtained shows a dark violet-brown azo-dyestuff image with goodabsorption for ultraviolet radiation. It is eminently suitable for useas an intermediate original for making further copies. The image on thecopy can easily be removed (erased) locally, for instance by scrapingoff parts of the hydrophilic layer containing the azo-dyestufl image.

A copy also having good absorption of the azo-dyestuif image is obtainedupon development With the Weakly alkaline developing liquid described inExample I. In this case the azo-dyestuff image has a brown shade.

If the hydrophilic polyvinyl acetate layer is impregnated with asensitizing liquid prepared in the same way, but starting from4-N-methyl-N-cyclohexylamino-3-chloroaniline, after the drying process alight-sensitive material is obtained which practically cannot bedeveloped with the weakly acid developing liquid. A reasonable, thoughvery sloW, development is achieved if the quantity of 1,3,6-naphthalenetrisulphonic acid sodium salt is reduced to one third of the originalquantity.

Copies made on such material show a less strong darkbrown azo-dyestufl?image of a lighter shade, having good absorption for ultravioletradiation.

We claim:

1. One-component diazotype material, comprising a support carrying alight-sensitive layer containing a diazo compound of the generalformula:

in which X is an anion, R and R are selected from the class consistingof chlorine and bromine atoms, and R is selected from the classconsisting of a cyclohexyl radical and methyl substituted cyclohexylradicals.

2. One-component diazotype material according to claim 1, said supportcomprising a transparent sheet material coated with a film layer of ahydrophilic colloid formed by hydrolysis of an ester selected from thegroup consisting of cellulose and polyvinyl esters, which film layercontains said diazo compound together with a stabiliz/er selected fromthe group consisting of 1,3,6-naphthalene itrisulfonic acid andwater-soluble salts thereof.

3. One-component diazotype material according to claim 2, characterizedin that the diazo compound is present in the film layer in the form ofthe zinc chloride double salt of said compound.

4. One-component diazotype material comprising a support carrying alight-sensitive layer containing a salt of 4 Nmethyl-N-cyclohexylamino-3,6-dibromodiazobenzene.

5. One-component diazotype material comprising a support carrying alight-sensitive layer containing a salt of 4 Nmethyl-N-cyclohexylamino-3,6-dichloro-diazobenzene.

6. One-component diazotype material comprising a support carrying alight-sensitive layer containing a salt of4-N-methyl-N-cyclohexylamino-3-chloro-6-brom0-diazobenzene.

7. One-component diazotype material comprising a support carrying alight-sensitive layer containing a salt of 4-N-1nethyl-N-(methyl)cyclohexylamino-3,6-dichlorodiazobenzene.

References Cited by the Examiner UNITED STATES PATENTS 2,067,132 1/1937Schnitzpahn et al. 260-141 2,405,523 8/1946 Sease et al. 9691 X2,548,845 4/1951 Neumann 9691 2,552,354 5/1951 Von Glahn et al. 96912,618,555 11/1952 Reichel 96-91 X 2,793,118 5/1957 Sanders et al. 96912,996,381 8/1961 Oster et al. 9691 X FOREIGN PATENTS 682,353 11/1952Great Britain.

I. TRAVIS BROWN, Acting Primary Examiner.

NORMAN G. TORCHIN, ALEXANDER D. RICCI,

Examiners.

R, L. STONE, R. SMITH, Assistant Examiners.

1. ONE-COMPONENT DIAZOTYPE MATERIAL, COMRPISING A SUPPORT CARRYING ALIGHT-SENSITIVE LAYER CONTAINIG A DIAZO COMPOUND OF THE GENERAL FORMULA: